In the related art, an angular-speed sensor of this type is introduced, for example, in Japanese Patent Unexamined Publication No. 11-173850. FIG. 4 is a plan view of an angular-speed sensor transducer presented in this publication.
In FIG. 4, tuning-fork type transducer 101 formed of silicon includes arms 102, 103. Arms 102, 103 are connected by base portion 104. Base portion 104 for causing arms 102, 103 to perform fork oscillation in the X-axis direction is formed with drive element members 105, 106. Monitor element members 107, 108 are formed on arms 102, 103 separately for monitoring amplitude of the fork oscillation in the X-axis direction of arms 102, 103. Detection element members 109, 110 are formed on arms 102, 103 for detecting the angular speed.
When an alternating-current signal is applied to drive element members 105, 106, arms 102, 103 perform the fork oscillation in the X-axis direction. Monitor element members 107, 108 are provided on arms 102, 103 at outer sides of the center lines of the shorter direction thereof.
Accordingly, monitor element members 107, 108 generate alternating-current signals of the same phase with respect to each other. Arms 102, 103 are controlled in response to output signals from monitor element members 107, 108 so as to achieve the fork oscillation of predetermined amplitude. When an angular speed is applied to arms 102, 103 about a Z-axis thereof when being in fork oscillation in the X-axis direction, arms 102, 103 are bent in a Y-axis direction thereof in the direction apart from each other. The magnitude of the applied angular speed can be found by detecting the bending by detection element members 109, 110.
In the angular-speed sensor in the related art as described above, monitor element members 107, 108 are provided separately on arms 102, 103 at outer sides of the center lines thereof. Therefore, the alternating-current signals of the same phase with respect to each other are generated. Therefore, there arises a problem such that monitor element members 107, 108 cannot cancel a noise to be removed at the time of the fork-driving in the X-axis direction, and hence are driven according to monitor signals containing the noise mixed therein.
Since drive element members 105, 106, monitor element members 107, 108 and detection element members 109, 110 must be provided independently on tuning-fork type transducer 101, it is difficult to realize downsizing of the angular-speed sensor. Since driving element members 105, 106, monitor element members 107, 108, and detection element members 109, 110 are provided independently on tuning-fork type transducer 101, when being used under a high-temperature environment as in the case of an automotive vehicle, the rate of variation in temperature is not uniform among the elements, and hence the respective elements are subjected to different changes over time. Therefore, there arises a problem such that the normal angular-speed signal cannot be obtained.
The invention provides a tuning-fork type transducer for an angular-speed sensor which realizes a stable fork-driving, realizes downsizing of the angular-speed sensor, and is capable of executing control of a vehicle body with high degree of accuracy when being used under a high-temperature environment, an angular-speed sensor using this transducer, and an automotive vehicle using this angular-speed sensor.